Experience and best practices http://biospecimens.cancer.gov/practices/) of the National Cancer Institute (NCI) indicate that the NCI Surveillance, Epidemiology and End Results (SEER) Program can support biospecimen research by creating a SEER-linked Virtual Tissue Repository (VTR). A SEER VTR, with its population representativeness and large sampling frame would be a unique resource for assembling robust collections of biospecimens, even for rare tumors and outcomes.